Bring milk and cream just to a boil in a 3-quart heavy saucepan over moderate heat, then remove from heat and whisk in dulce de leche until dissolved. Whisk in vanilla and transfer to a metal bowl. Quick-chill by putting bowl in a larger bowl of ice and cold water and stirring occasionally until cold, 15 to 20 minutes.

Freeze mixture in ice cream maker until almost firm, then fold in pecans if using them. Transfer ice cream to an airtight container and put in freezer to harden, at least 1 hour.

dulce de leche ice cream was originally published on smittenkitchen.com